The field of the invention is rear vision mirrors of the type used on trucks, automobiles and the like. The invention relates more particularly to anti-glare rear vision mirrors which are capable of reducing the discomfort resulting from headlights from a vehicle following the vehicle to which the mirror is attached.
Anti-glare rear vision mirrors are widely used in motor vehicles. The most common type of mirror has a partially reflective glass which is mounted in front of a tiltable completely reflecting mirror. In daylight use, both mirrors are aligned to reflect all light coming through the back window. At night, to reduce headlight glare, the completely reflecting mirror is tilted either upwardly or downwardly and the partially reflective mirror only is positioned to reflect the headlights. A reflected headlight thus is only partially reflected and the discomfort of glare is eliminated. Such approach is not normally used for rear vision mirrors of the type which are mounted outside of the vehicle and typically are mounted on the left door or door frame of the vehicle. The reason that this tilting approach is not successful for outside mirrors is that the completely reflective mirror which is tilted is still capable of reflecting everything in its line of view. When the mirror is mounted within a passenger compartment at night, the compartment is darkened and the tilted reflective mirror is positioned toward a darkened portion of the vehicle and thus reflects nothing which interferes with the view from the partially reflective mirror. In outdoor environments, however, this is not so and such mirrors are not believed to be useful when mounted onto the exterior of a vehicle.
Tinted glass or plastic sheets have been mounted on interior rear vision mirrors as shown in U.S. Pat. Nos. 2,327,802; 2,070,434 and 2,525,012. Such approaches, however, have not found use for exteriorly mounted rear vision mirrors and the discomforting glare is a common problem for truck drivers and others who rely on side mounted rear vision mirrors and who are required to drive long hours at night.